The objectives of the proposed research are to evaluate quantitatively the effectiveness of cooling therapy for the immediate treatment of burn injury, and to determine cooling regimens which result in the greatest inhibition in the manifestation of injury for varying degrees of wound severity. The study will utilize a unique experimental apparatus, (developed and fabricated by the project investigators) capable of precise measurement and control of the thermal parameters of the injury process and its treatment, combined with a direct, dynamic assessment of the physiological response of the microcirculation. A hamster check pouch is prepared for direct, continuous viewing of the microvascular bed in vivo on a specially modified light microscope. A heating and/or cooling stage is utilized to precisely regulate the tissue temperature and its time rate of change via a programmable, analogue temperature control system. The feedback signal for proportional control is provided from a 20 microns m microthermocouple in direct contact with the tissue specimen. The manifestation of injury is assessed by measurement of alterations in blood flow characteristics including velocity (via a closed-circuit video taping system), the degree of vasoconstriction/dilitation, the time wise progression for development of hemostasis, and the extent of edema (as determined by photometric measurement of the vascular leakage of narrow molecular weight cuts of fluorescent labled dextrans). Standard control burns of specified severity will be readily produced on this device by enforcing predetermined temperatures and durations of thermal trauma. Subsequently the specimen will be subjected to a cooling protocol, and alterations in the vascular response to burning measured. Various cooling regimens will be studied to determine (1) the optimum range the temperatures for cooling therapy, (2) the time limit beyond which cooling therapy exhibits no further benefit to the burn wound, and (3) the decrease in efficacy of cooling with progressively increasing delay in the initiation of therapy subsequent to thermal insult.